Solution of titanium and iron salts and the process of preparing same



UNITED STATES PATENT OFFICE.

HJALMAR OLSEN, 0F CHRISTIANIA, AND TORMOD REINERT FOBLAN D, OEHAUG-ESUND, NORWAY, ASSIGNORS .TO TITAN C0. A/S., OF CHRISTIANIA, NORWAY.

SOLUTION OF TITANIUM AND IRON SALTS AND THEPROCESS PREPARING SAME.

Specification of Letters Patent.

Patented Mar. 16, 1920.

No Drawing. Continuation of application Serial No. 169,107, filed Kay 16, 1917. This application filed October 12, 1917. Serial No. 196,316.

To all whom it may concern Be it known that we, HJALMAR OLSEN and TORMOD REINERT FoRLANo, subjects of Norway, and residents, respectively, of Christiania, and Haugesund, in the Kingdom of Norway, have invented certain new and useful Improvements in the Solutions of Titanium and Iron Salts and the Processes of Preparing Same, of which the following is a specification.

This invention relates to the production of titanium hydrates in a substantially pure condition from titaniferous materials in which iron is present. The object of the invention is the novel treatment of a solution from which a satisfactory yield of practically pure titanium hydrates can be precipitated while the iron remains in the solution.

When titaniferous materials containing iron, as for example, ihnenite, have been decomposed by a suitable decomposing agent, as for example, sulfuric acid, and'a solution obtained of the resultant product, that solution contains salts of tetravalent titanium and trivalent iron. When precipitation is brought about in such a solution, more or less of, the iron will be thrown down along with the titanium hydrates and the precipitate thus obtained will be more or less discolored. For certain. uses, particularly where the titanium hydrates are to be used for the manufacture of light colored pigments, it is desirable that the precipitate be white or nearly so in color. To attain this, it is necessary that it be practically free from iron.

Numerous methods have been proposed to bring this about, such for instance as the complete reduction of both the dissolved iron and titanium, orthe reduction of the iron by the addition of sulfurous acid or similar reducing agents, or the reduction of the iron in the presence of free acids. The first of these methods results in a very poor yield sufliciently reduced to permit the hydrolysis of the titanium salts.

We have discovered a method whereby not proceed to a point Where a titanous compound will be thrown down with the precipitate.

In the Norwegian Patent No. 27292, November l, 1915', (which is embodied in United States patent application Serial No. 196,977, filed by Gustav J ebsen on October 12,1917,) is disclosed a process of preparing a solution from titaniferous material by the use of sulfuric acid or other suitable decomposing agents and we have found the solution preparedv in accordance therewith very Well adapted for the treatment comprising this invention. This solution will be referred to herein as a convenient one for the description of our invention, but it is to be understood that it is made use of solely for illustrative purposes and that our invention is not limited to the treatment of that particular solution.

Taking up now the specific illustration of the method of carrying out our process, we prefer to conduct the same by means of electrolysis. To that end we make use of a suitable electrolytic vat equipped with an'unglazed porcelain cell of the usual diaphragn'i variety in which the anode is mounted, the cathode being located in the large area of the vat. Dilute sulfuric acid about 30 per cent. H,SO in strength is placed in the anode compartment The vat is so arranged 'that there is a constant intake and overflow of the solution and in such a manner that the desired reduction takes place" throughout the solution. Suitable current is supplied and the solution is circulated throughthe vat and subjectedto electrolysis as above indicated. The particular solution chosen for illustration contains in most cases not only tetravalent titanium alts and trivalent iron salts, but also divalent iron salts and certain other compounds. The solution is further characterized by containing acid in substantially no greater quantity than is required to form normal salts with the baseforming material present. The solution is submitted to electrolysis until all of the trivalent iron salts are reduced to the divalent condition and until the desired reduction has taken place in the titanium salts. This latter reduction should preferably be terminated when just suflicient reduced titanium is obtained to prevent reoxidization of the iron during the precipitation. This assures that the precipitate will be practically free from iron; if carried much beyond I this point a titanous compound will be thrown down with the titanic hydrate anddiscoloration of the precipitate will result. Should, however, the reduction be carried too far, some of the unreduced solution may be added to the solution under treatment and the over-reduction thus corrected.

The solution prepared as above is now ready to be submitted to precipitation. So far as concerns the method of effecting precipitation, that preferred is the method disclosed in Norwegian Patent No. 27,917, October 6, 1916, (which is embodied in United States Letters Patent No: 1,288,863 granted December 24, 1918;) but it should be understood that the solution prepared in accordance with our invention is suitable for precipitation in any well known manner. This method is indicated as preferred because, due to the fact that it contemplates precipitation from a concentrated solution,

our solution can be immediately transferred from the electrolytic vat into a precipitation vat and considerable time and expense incident to dilution thus avoided.

The .word hydrates as used herein is applied as a general term and includes hydrated oxids with or without more. or less basic salts or adsorbed acids.

The foregoing detailed description has been given for clearness of understanding and no undue limitation should be deduced therefrom, but the ap ended claims should be construed as broadly as permissible. in view of the prior art.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. The process of preparing for precipitationa solution containing tetravalent titanium salts and trivalent iron salts, which consists in reducing all of the trivalent iron salts to divalent iron salts and reducing so much of the tetravalent titanium salts to titanium salts of a lower valence as will prevent a reoxidization of the iron during subsequent precipitation of the titanium hydrates.

2. The process of preparing for precipitation a solution containing tetravalent titanium salts and trivalent iron salts, which consists in reducing all of the trivalent iron salts to divalent iron salts and reducing so much of the tetravalent titanium salts to titanium salts of a lower valence as will prevent a reoxidization of the iron during sub sequent precipitation of the titanium hydrates, whereby a precipitate can be thrown down substantially free from iron and titanous compounds.

3. The process of preparing for precipitation a solution containing tetravalent titanium hydrates and trivalent iron salts, which consists in electrolytically reducing all of the trivalent iron salts to divalent iron salts and reducin so much of the tetravalent titanium sa ts to titanium salts of a lower valence as will prevent a reoxidization of the iron during subsequent precipitation of the titanium hydrates, whereby a precipitate can be thrown down substantially free from iron and titanous compounds.

4. As a new and useful article of manufacture, a solution of titanium and iron salts adapted for the precipitation of titanium hydrates substantially free from iron," in which solution the iron is in the'divalent condition and the titanium in both the tetravalent condition and in a condition of lower valence, the salts of the last-named titanium being resent in relatively small proportion to t e salts of the tetravalent titanium but in suflicient quantity to prevent the formation of trivalent iron salts on sub sequent precipitation of the titanium hy-* drates. I i

5. As a new and useful article, a solution of titanium and iron salts adapted for the precipitation of titanium hydrates char acterized by containing acid in substantially no greater quantity than is required to form normal salts with the base-forming material resent and in which the iron is in the diva ent condition and the titanium in both the tetravalent condition and in a condition of lower valence, the last named titanium salts being present in sufficient quantity to prevent the formation oftrivalent iron salts on precipitation of the titanium hydrates. Slgned at Christiania, Norway, on this Norway, on the 13th of Septr., 1917.

HJALMAR OLSEN. TOR-MOD REINEitT FllRLAND. Witnesses to signature of Tormod Reinert' Forland at Bergen:

H. S. WATERMAN, A. CLEMENTSEN.

12th day of September, 1917, and at Bergen, 

